It is known to use a spring to engage an impeller clutch as shown and described in commonly assigned U.S. patent application Ser. No. 14/458,851, for example, hereby incorporated by reference as if set forth fully herein. It is also known to use a single pressure chamber to apply an impeller clutch and a torque converter clutch, keeping the torque converter clutch disengaged by a spring during torque converter operation, as shown and described in commonly assigned U.S. Pat. No. 8,607,948 and United States Patent Application Publication No. 2013/0140122, for example, both hereby incorporated by reference as if set forth fully herein.